diff --git a/dcc/concat.py b/dcc/concat.py
index 6493037..b0af14f 100644
--- a/dcc/concat.py
+++ b/dcc/concat.py
@@ -1,6 +1,7 @@
 import av
 import copy
 import dcc.doom_base
+import enum
 import fractions
 import io
 import logging
@@ -9,6 +10,11 @@ import numpy as np
 import wand.image
 
 
+class State(enum.Enum):
+    NOT_STARTED = 1
+    STARTED = 2
+    DONE = 3
+
 class Concat(dcc.doom_base.Wad):
     def get_parser(self, prog_name):
         parser = super().get_parser(prog_name)
@@ -21,10 +27,7 @@ class Concat(dcc.doom_base.Wad):
         logging.basicConfig()
         av.logging.set_level(av.logging.VERBOSE)
         av.logging.restore_default_callback()
-        videos = (
-            self.fabricate.joinpath(parsed_args.wad)
-            .glob(f"{parsed_args.wad}_map*.mp4")
-        )
+        videodir = self.fabricate.joinpath(parsed_args.wad)
         fn_base = (
             f"{parsed_args.wad}_maps{parsed_args.start_map}"
             + f"to{parsed_args.end_map}"
@@ -45,19 +48,27 @@ class Concat(dcc.doom_base.Wad):
         # unavailable" error when switching to inputs after the first.
         # Presumably fixable, but it's easier to just make one graph per video
         # and mux everything together at the end.
-        for v in sorted(videos):
-            # TODO: Support UDoom in literally any way.
-            if not (
-                v.name >= f"{parsed_args.wad}_map{parsed_args.start_map}.mp4"
-                and v.name <= f"{parsed_args.wad}_map{parsed_args.end_map}.mp4"
-            ):
+        # TODO: Support UDoom in literally any way.
+        d2maps = [str(x).zfill(2) for x in range(1,16)] + ["31","32"] + [str(x) for x in range(16,31)]
+        state = State.NOT_STARTED
+        for idx in d2maps:
+            if idx == parsed_args.start_map:
+                state = State.STARTED
+            if idx == parsed_args.end_map:
+                state = State.DONE
+            if state == State.NOT_STARTED:
                 continue
             start_time = self._offset / 1000000
-            text = self._add_chunk(v, output, not parsed_args.nooverlay)
+            text = self._add_chunk(
+                videodir.joinpath(f"{parsed_args.wad}_map{idx}.mp4"),
+                output, not parsed_args.nooverlay
+            )
             list.append(
                 summary, f"{text} {math.floor(start_time / 60):02}:"
                 + f"{math.floor(start_time % 60):02}"
             )
+            if state == State.DONE:
+                break
         output.close()
 
         for line in summary: